1. Field of the Invention
The invention relates to methods and apparatus for treating surfaces of articles, such as semiconductor wafers, adapted to reduce buildup of electrostatic charge.
2. Description of Related Art
Semiconductor wafers undergo a variety of wet processing stages during manufacture of integrated circuits. To accommodate such processes, a single wafer may be supported in relation to one or more treatment fluid nozzles by a chuck associated with a rotatable or non-rotatable carrier. Wafer-supporting chucks are described for example in U.S. Pat. Nos. 4,903,717, 5,513,668, 6,435,200 and 6,536,454.
It is known that semiconductor wafer processing can result in unwanted buildup of static charge on the wafer surface. For example, in European Patent Application No. 1,077,473 it is described that buildup of static charge may be reduced by introducing carbon dioxide to a deionized water processing fluid so as to render the processing fluid electrically conductive. That method does not directly address the potential for static charge buildup in wafer-handling components that are not contacted by the electrically conductive processing fluid and, in any event, it precludes the use of relatively non-conductive processing fluids such as deionized water and 2-propanol. U.S. Pat. No. 7,335,090 relates to a spin chuck having holding pins which are formed of conductive resin and associated with a stainless steel shaft, which in turn is supported by radial metal bearings. However, the presence of a steel shaft creates a risk that a semiconductor wafer may be contaminated with iron, which should be avoided. Also, the connection between the stainless steel shaft and the resin pins is not specified, and connections through radial bearings likely are unreliable electrical contacts due, e.g., to the presence of bearing lubricants.